Carbon fiber reinforced plastic (CFRP) is being used in place of metal, especially in applications where relatively low weight and high mechanical strength are desirable. Structures made of carbon fiber reinforced plastic are desirable for commercial and military aircraft.
For aircraft structures subject to extreme loading conditions, however, all-metal composition is still favored. One such structure is a keel beam, which is a longitudinally oriented structural member that imparts flexural stiffness to the fuselage, particularly where the landing gear is located and where the wing assemblies of the aircraft are joined to the fuselage.
It would be desirable to use composite materials in keel beams and other aerospace structures subject to extreme loading conditions.